Fabrication and characterization of ferroelectric composite ceramics

Abstract

New composites of Ba_1-xSr_xTiO₃ (BSTO) and nonferroelectric oxide ceramic composites with lower barium content have recently been formulated. The electronic properties of the materials including the temperature dependent properties of the dielectric constant have been investigated. The materials exhibit reduced dielectric constants, ϵ ', and loss tangents, tan δ, which reduce the overall impedance mismatch and the insertion loss of the device. In addition, the tunability, change in the dielectric constant with applied voltage, is maintained at a sufficiently high level for all dielectric constants of interest. Some initial work on the microwave properties of the materials using a cylindrical TE₀₁ mode-filtered X-band cavity have been investigated. Fourier Transform Raman spectra were taken to provide a compositional analysis of the specimens and to provide insight into the effect of strontium and oxide additives on the structural properties. These properties have been correlated to the electronic and the microwave properties of the composite ceramic materials.